Photofragmentation laser-induced fluorescence of ozone using narrowband and broadband KrF excimer lasers

Abstract

Photofragmentation laser-induced fluorescence (PF-LIF) is used for the high-sensitivity measurement of ozone density; however, its theoretical basis is not well established. In this paper, O3 PF-LIF, using a tunable KrF excimer laser (248–249 nm), was examined using both measurements and calculations to provide a theoretical basis for this measurement method. The KrF laser photolyzed O3 to produce O, which was then measured using LIF with the same laser pulse that had photolyzed the ozone. A calculation including photochemical reactions and a LIF model of O reproduced the measured results well which demonstrated the reliability of the calculation. A recommended laser energy density of 100–400 mJ cm−2 was obtained by considering the depletion of ozone by the laser photolysis and the saturation of the LIF. It was also demonstrated that a broadband KrF excimer laser, which is not line narrowed and therefore not tunable, could also be used for O3 PF-LIF. The signal intensity of the broadband PF-LIF was only reduced to 1/2–1/3 of the narrowband PF-LIF.